Digital dat recording/reproducing apparatus

ABSTRACT

A digital data recording/reproducing apparatus which divides each of information data pieces into a plurality of cells, further divides each of the cells into a series of a plurality of units, and records the units. The digital data recording/reproducing apparatus has means for recording a required time for reproduction until the head position of a unit is reached, with reference to the head position of an information data cell to which a cell belongs, as a unit start time, in addition to each of the units, and means for recording a cell start time (T s ) equal to a required time for reproduction until the head position of each of the cells is reached, and a required time for reproduction (P s ) of each of the cells in a management data region.

This is a continuation of application Ser. No. 09/271,989 filed on Mar.19, 1999 now U.S. Pat. No. 6,445,873.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a digital datarecording/reproducing apparatus, and more particularly to a digital datarecording/reproducing apparatus for recording/reproducing digital datacompressed in accordance with a variable bit rate encoding scheme.

2. Description of Related Background Art

At present, widespread video and audio media include a laser disk (LD),a VHS video and so on in the analog scheme, and a mini-disk (MD), acompact disc (CD) and so on in the digital scheme. On the other hand, aspackage media for the next generation, technological developments havebeen vigorously advanced for practical use of a rewritable digitalversatile disk (DVD-R/W) which enables recording and reproduction ofimages and sound with high quality for a long time. In a recordingmethod using DVD-R/W, information data pieces such as a movie, audio andso on can be recorded on a disk in high density. Image data arerecorded/reproduced in accordance with a highly efficient encodingscheme such as MPEG2, while audio data are recorded/reproduced inaccordance with compression schemes such as PCM, AC3 or the like. In thefollowing, a collection of data such as a full program, a full movie orthe like is called an “information data piece”, and data which includesone or a plurality of information data piece is called an “informationdata group”.

In a recording/reproducing scheme for a conventional recordable anderasable digital data recording/reproducing apparatus, for example, MD,an audio information data piece is again divided into a plurality ofsubpieces, each of which is given address information that is relied onto display a playing time and to search for particular data. Statedanother way, since MD has a fixed compression ratio for audio data, anactually required time for reproduction can be unitarily calculated bymultiplying the amount of data by a playing time per unit time.Therefore, a data region is comprised only of audio data and does notinclude time information on reproduction.

However, as a method of extending a recording time for images, DVD-R/Whas employed a “variable bit rate coding: VBR” which changes the amountof codes in accordance with a change in the amount of information in animage in place of a conventional “constant bit rate coding: CBR”, sothat an actually required time for reproduction cannot be calculateddirectly from the amount of compressed data. In other words, it is notpossible to use a conventional approach of deriving a playing time fromthe address of a reproduced position. Also, while DVD-R/W has a featureof providing an erasable recording medium, recorded time informationbecomes discontinuous if the user erases a desired region or the like,thereby causing impediments to a time search, a playing time display,and so on.

OBJECT AND SUMMARY OF THE INVENTION

As described above, when digital data compressed using a variable bitrate coding is recorded/reproduced, a time required for reproductioncannot be derived directly from the address of a reproduced position,thereby giving rise to a problem that a time search, a playing timedisplay, and-so on are prevented. The present invention has been made inview of the problem as mentioned, and its object is to provide a digitaldata recording/reproducing apparatus which is capable of derivingplaying-time information even on a midway position of information datathat has undergone editing such as chapter setting, erasure or the likeafter recording, when such information data is reproduced from themidway position.

To achieve the above object, the present invention provides a digitaldata recording/reproducing apparatus for dividing each of informationdata pieces into a plurality of segments to sequentially record thesegments in an information data region on a recording medium,additionally recording a plurality of management data corresponding toeach of one or a plurality of information data groups each including oneor a plurality of the information data pieces, in a management dataregion on the recording medium, and reproducing the information datapieces on the basis of the management data. The digital datarecording/reproducing apparatus comprises means for dividing each of thesegments into a series of a plurality of units, and recording a requiredtime for reproduction from a head position of an information data piece,to which the segment belongs, to a head position of each of the units asa unit start time in addition to each of the units, and means forrecording a segment start time (T_(s)) equal to a required time forreproduction from a head position of an information data piece, to whichthe segments belong, to ahead position of each of the segments, and arequired time for reproduction (P_(s)) of each of the segments in themanagement data region.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating the configuration of a digitaldata recording/reproducing apparatus according to the present invention;

FIG. 2 is a schematic diagram for explaining the structure of data whichis recorded on a disk;

FIG. 3 is a schematic diagram for explaining the structure of data andtime information which are recorded on a disk according to the presentinvention;

FIG. 4 is a schematic diagram showing a data structure and recordingregions according to the present invention;

FIG. 5 is a table showing attribute information data according to thepresent invention;

FIG. 6 is a flow chart illustrating a procedure for a recordingoperation processing routine according to the present invention;

FIG. 7 is a flow chart illustrating a procedure for a reproducingoperation processing routine according to the present invention;

FIG. 8 is a flow chart illustrating a procedure for a cell divisionprocessing routine according to the present invention;

FIG. 9 is a flow chart illustrating a procedure for a cell erasureprocessing routine according to the present invention;

FIG. 10 is a flow chart illustrating a procedure for a playing timecalculation routine according to the present invention; and

FIG. 11 is a flow chart illustrating a procedure for a time searchroutine according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of the present invention will hereinafter be described indetail with reference to the accompanying drawings.

FIG. 1 illustrates the configuration of a digital datarecording/reproducing apparatus according to the present invention.

The digital data recording/reproducing apparatus in FIG. 1 is providedwith an analog audio signal and video signal, for example, from atelevision tuner or the like as a source. An input audio signal isconverted to a digital form by an A/D converter 2, and supplied to anaudio encoder 3, while a video signal is converted to a digital form byan A/D converter 4 and supplied to a video encoder 5.

The audio encoder 3 applies a predetermined code conversion (forexample, data compression processing) to a digital audio signal, andsupplies its code converted output to a first input of a multiplexer 8.The video encoder 5 applies a predetermined code conversion (forexample, compress processing) to a digital video signal, and suppliesits code converted output to a second input of the multiplexer 8. Themultiplexer 8 is also supplied at a third input thereof with anmanagement data signal produced by a system control circuit 10. Themultiplexer 8 time-division-multiplexes the first, second and thirdinput signals to produce a multiplexed information signal composed ofthe audio and video information data signals and the management datasignal.

The multiplexed information signal is supplied to arecording/reproducing control circuit 15 and recorded on a rewritablerecording medium such as a rewritable DVD-R/W or the like.

In a reproducing mode for reproducing recorded information on arecording medium 17, the recording/reproducing control circuit 15supplies a multiplexed information signal read by arecording/reproducing head 19 to a demultiplexer 22. The demultiplexer22 time-division-demultiplexes the multiplexed information signalsupplied thereto to separately output an audio signal, a video signaland a management data signal equivalent to those at the respectiveinputs of the multiplexer 8.

An audio signal output from the demultiplexer 22 is supplied to an audiodecoder 23 which applies the audio signal with conversion processingreverse to the code conversion performed in the encoder 3 (for example,decompression processing). The reversely converted output is furtherconverted to an analog form by a D/A converter 24 and delivered as ananalog audio output. A video signal output from the demultiplexer 22 issupplied to a video decoder 25 which applies the video signal with aconversion processing reverse to the code conversion performed in theencoder 5 (for example, decompression processing). The reverselyconverted output is converted to an analog form by a D/A converter 26and delivered as an analog video output.

In a recording mode for recording audio and video signals, arecording/reproducing head 19 writes a multiplexed information signalinto a recording medium 17 in a predetermined format under the controlof the recording/reproducing control circuit 15 which followsinstructions from the system control circuit 10. In this event, themultiplexed information signal is also supplied to the demultiplexer 22.The flow of signal processing in successive components including thedemultiplexer 22 subsequent to the recording/reproducing control circuit15 in the recording mode is similar to the foregoing.

A recording medium 17 loaded into the recording/reproducing apparatus ofthe present invention may be a recording medium which permitsoverwriting of information previously recorded thereon, other than theaforementioned DVD-R/W.

The system control circuit 10 also issues instruction signals forcontrolling a read operation and a write operation to therecording/reproducing control circuit 15. Any of these instructionsignals includes address information indicative of an actually recordedposition or a region on a loaded recording medium. With the addressinformation, information can be written at an arbitrary recordingposition on the recording medium, and information can be read from anarbitrary recorded position. Briefly, the system control circuit 10performs an address control for accessing an arbitrary recorded positionon a recording medium in the reproduction and recording modes forreproducing and recording information from and on the recording medium.

The system control circuit 10 further controls other components inresponse to instruction signals from a manipulation unit 30 serving as auser interface unit. Representative ones of the instruction signalsinclude recording/reproducing instructions, and editing instructionssuch as a chapter setting instruction or an erasure instruction during areproduction or recording operation. Therefore, the manipulation unit 30serves as change instruction generating means for generating a changeinstruction in an editing mode.

The system control circuit 10 can force associated components to performoperations in accordance with the contents of manipulations of themanipulation unit 30, using a memory 35 for storing data indicative ofthe aforementioned recording/reproducing or edit instruction, and dataread from the recording medium 17.

While the foregoing description has been made for a digital datarecording/reproducing apparatus, taken as an example, which is suppliedwith data from a television tuner or the like as a source, the presentinvention is not limited to such a configuration. Alternatively, thedigital data recording/reproducing apparatus of the invention may take aform in which external input terminals for audio and video signals areprovided for directly leading them to the multiplexer 8, instead ofproviding a television tuner, A/D converters 2, 4 and encoders 3, 5,such that these external input terminals can be supplied with an audiodigital signal and a video digital signal which have previouslyundergone code conversions such as those executed in the encoders 3, 5.

The system control circuit 10 and the recording/reproducing controlcircuit 15 are commonly used as recording control means and reproductioncontrol means.

Next, the embodiment of the present invention will be described withreference to the accompanying drawings.

FIG. 2 shows the structures of an information data group and managementdata which are recorded on a recording medium. VMGI stores disk commondata associated with the information data group, which is data forgenerally managing a disk, for example, menu data or the like for adisk. Video Object Set (VOBS) is an information data group whichcollects one or a plurality of Video Objects (VOB), each of which is aset of information data pieces, for example, a full program, a fullmovie or the like. Video Title Set Information (VTSI) is management dataassociated with VOBS. BUP is backup data for VTSI, and contains the samecontents as VTSI. VOB is further divided into a plurality of segments,each of which is hereinafter called a “cell.”

FIGS. 3 and 4 are schematic diagrams for explaining an example of a datastructure recorded on an optical disk which serves as a recording mediumin the digital data recording/reproducing apparatus according to thepresent invention. In the present invention, each of cells is dividedinto a series of plural units as shown in FIG. 3, and a required timefor reproduction (t_(s,u)) from the head position (time T=0) of aninformation data piece, to which a cell belongs, to the head position ofeach of the units is additionally recorded in the cell as a unit starttime. Further, a cell start time (T_(s)) equal to a required time forreproduction from the head position of an information data piece, towhich a cell belongs, to the head position of each of the units, as wellas the unit start time (t_(s,u)) are recorded in VTSI. A required timefor reproduction (P_(s)) of each of cells is also recorded in VTSI.

In the present invention, when a plurality of information data groupsare recorded, respective management data VTSI #i (i=1,2, . . . ) arecollectively recorded at predetermined positions on the disk, forexample, in a management data region defined in an inner peripheralregion, as shown in FIG. 4. Also, backup data BUP #i (i=1,2, . . . ) aresimilarly recorded in a recording region. In this event, BUP #i ispreferably recorded continuously to the recording region for VTSI #i.Further, the disk common data VMGI is also recorded in the managementdata region. For the management data region, a sufficient recordingregion has been previously reserved for recording a presumably maximumamounts of VTSI #i and BUP #i. While information data groups arerecorded in an information data region, VOB need not be recorded in theorder of VTSI corresponding thereto, and empty regions may be includedtherein.

In the present invention, the management data VTSI further includesattribute information data indicative of a recording scheme for each ofthe information data groups VOBS. The attribute information dataincludes video display information such as an encoding scheme forconvenience of decoding, as well as a scanning speed, the number ofscanning lines, an aspect ratio and so on for convenience of displayingreproduced data. For example, in an example shown in FIG. 5, theattribute information data is classified into 12 modes. The informationdata groups are recorded or reproduced on the basis of the attributeinformation data, wherein the same kind of attribute information data ispreferably recorded in the same VTSI.

In the following, recording and reproducing operations of the digitaldata recording/reproducing apparatus, which is an embodiment of thepresent invention, will be described with reference to the flow chartsshown in FIGS. 6-11.

FIG. 6 illustrates an example of a procedure for a recording operationprocessing routine executed by the system control circuit 10. The systemcontrol circuit 10 fetches settings for a recording instruction or thelike such as a recording mode and a recording time, entered by the userthrough the manipulation unit 30, from the memory 35 (step 11). Then,the system control circuit 10 issues an instruction to therecording/reproducing control circuit 15 to record audio/video data(hereinafter called the “AV data”) and unit start times (t_(s,i), i=1,2,. . . ) in an empty region within the information data region in adesired recording mode (step 12). The system control circuit 10determines whether or not an interrupt instruction has been entered bythe user through the manipulation unit 30, such as a cell divisioninstruction, i.e., chapter setting or the like (step 13). Continuing thedescription with reference to FIG. 3, when an interrupt instruction hasbeen entered for chapter setting or the like, the system control unit 10assigns the unit start time (t_(s,u)) at the time the interruptinstruction has been entered (assuming the time of a unit #u in a cell#S) to a new cell start time (T_(s,2)), and stores in the memory 35 thenew cell start time (T_(s,2)) together with a required time forreproduction (P_(s,l))of a newly created preceding cell (units #1 to#u−1) after the division (step 14). Next, the system control circuit 10determines whether or not the AV data has been recorded on the basis ofthe recording settings by the user (step 15). If the AV data has beenrecorded, the recording operation is terminated (step 16). Next, thesystem control circuit 10 fetches management data previously stored inthe memory 35 from the memory 35 (step 17). It should be noted that thedigital data recording/reproducing apparatus according to the embodimentreads all management data recorded in a management data region of a diskand stores them into the memory 35, when the disk was loaded thereinto,such that the management data is managed on the memory 35 while the diskis loaded in the apparatus. Next, the system control circuit 10determines whether or not the attribute information data of the recordedAV data has already been included in the management data (step 18). Ifalready included, VTSI including the same attribute information data asthat of the just recorded AV data is overwritten by the managementinformation (step 19). If the same attribute information data has notbeen included, VTSI including the management data and the attributeinformation data are newly recorded in addition to the existing VTSI(step 20), followed by the completion of the recording operationprocessing.

FIG. 7 illustrates an example of a procedure for a reproducing operationprocessing routine executed by the system control circuit 10. The systemcontrol circuit 10 fetches settings for a desired program to bereproduced or the like, entered by the user, from the memory 35 (step31). Next, the system control circuit 10 retrieves management datapreviously read from a disk and stored in the memory 35, when the diskwas loaded, from the memory 35 (step 32), and identifies a mode andmanagement data associated with the desired program to be reproducedfrom the retrieved management data (step 33). Next, the system controlcircuit 10 issues an instruction to the recording/reproducing controlcircuit 15 to reproduce AV data associated with the desired programbased on the identified mode and management data (step 34). The systemcontrol circuit 10 determines whether or not the AV data based on thesettings has been reproduced (step 35), and issues a reproduction stopinstruction if the AV data has been reproduced (step 36), followed bythe completion of the reproducing operation processing.

FIG. 8 illustrates an example of a procedure for a cell divisionprocessing routine for editing such as chapter setting, erasure or thelike. The system control circuit 10 calls are producing routine, andinstructs a disk reproducing operation (step 41). Describing withadditional reference to FIG. 3, when a cell division signal is enteredfrom the manipulation unit 30 during reproduction, the system controlcircuit 10 fetches the signal (step 42), and extracts a unit start time(t_(s,u)) at that time from the reproduced data (step 43). Next, thesystem control circuit 10 fetches a required time for reproduction(P_(s)) and a cell start time (T_(s)) of a cell, to which the unitbelongs before division, from the memory 35 in which such data read froma disk have been stored when the disk was loaded (step 44). Next, thesystem control circuit 10 calculates required times for reproduction(denoted by P_(S,1), P_(S,2), respectively) of the two divided cellsfrom the foregoing three values (P_(s), T_(s), t_(s,u)) (step 45). Then,the system control circuit 10 deletes the required time for reproducingthe cell (P_(s)) and the cell start time (T_(s)) before the divisionfrom the memory 35 (step 46), and stores the required times forreproducing the resultant cells (P_(s,1), P_(s,2)) and cell start times(denoted by T_(s,1), T_(s,2), respectively) in the memory 35 (step 47).The system control circuit 10 determines whether or not the celldivision processing has been terminated (step 48), and repeats the flowfrom the fetching of signals (step 42) if not terminated, and issues areproduction stop instruction if the cell division processing has beenterminated (step 49). Then, the system control circuit 10 issues aninstruction to the recording/reproducing control circuit 15 to recordthe management data stored in the memory 35 in the management dataregion on the disk (step 50), followed by the completion of the celldivision processing.

FIG. 9 illustrates an example of a procedure for a cell erasureprocessing routine during editing. The system control circuit 10 fetchesdesired cell erasure settings entered by the user from the memory 35(step 61), and deletes a playing time and a cell start time of a cell,which has been specified for erasure, from management data on the memory35 (step 62). Next, the system control circuit 10 determines whether ornot the specified cell has been erased (step 63), and repeats the flowfrom the deletion of data from the memory (step 62) if not erased, andissues an instruction to the recording/reproducing control circuit 15 torecord the management data stored in the memory 35 in the managementdata region on the disk (step 64) if erased, followed by the completionof the cell erasure processing.

FIG. 10 illustrates an example of a procedure for a playing timecalculation routine for use by the system control circuit 10 during areproducing operation. The system control circuit 10 fetches a requiredtime for reproduction (P_(i)) and a cell start time (T_(i)) of each ofcells in an information data piece, which has been specified forreproduction, from management data on the memory 35 (step 71). Then, thesystem control circuit 10 fetches a unit start time (t_(s,u)) of a unitunder reproduction (step 72), calculates the sum of a total sum ofrequired times for reproduction of cells preceding to the cell underreproduction (ΣP_(i); i=1,2, . . . ,s−1) and the value derived bysubtracting a cell start time of the cell under reproduction from theunit start time of the unit under reproduction (t_(s,u)−T_(s)), andassigns the resultant value as a playing time (step 73). Therefore, evenif a cell preceding to the cell under reproduction, for example, a cell#k (1<k<S) has been already erased, a required time for reproduction(P_(k)) of the erased cell is not included in the sum (ΣP_(i)) of therequired times for reproduction of the cells, thus making it possible tocorrectly calculate a playing time. The playing-time calculationprocessing is completed after executing the foregoing steps.

FIG. 11 illustrates an example of a procedure for a time search routinefor searching for a reproduced position based on a playing time. Thesystem control circuit 10 fetches a desired reproduction time from thememory 35 (step 81), and instructs the recording/reproducing controlcircuit 15 to perform a reproducing operation near the positioncorresponding to the desired reproduction time (step 82). Next, thesystem control circuit 10 calls the playing-time calculation routine tocalculate the playing time at the current position from a unit starttime (t_(s,u)) of a unit under reproduction, and makes a search suchthat the calculated playing time is coincident with the desiredreproduction time (step 83). Then, the system control circuit 10determines whether or not the calculated playing time is equal to theset time (step 84), and completes the time search processing at the timethey are equal.

As previously described above with reference to FIG. 3, according to thepresent invention, by using a unit start time read from a reproducedposition, and a cell start time and a required time for reproduction ofa unit recorded on a recording medium and stored in a memory, whilerelying on the head position of a information data piece underreproduction as a reference time, it is possible to realize a digitaldata recording/reproducing apparatus which is capable of readilyperforming a calculation of a reproduction elapsed time at an arbitraryreproduced position, a time search, and so on even if an informationdata piece, which has undergone editing such as chapter setting, erasureor the like after recording, is to be reproduced from a midway position.Also, by including attribute information data indicative of areproducing scheme for information data groups in management data, andrecording or reproducing the information data groups on the basis of theattribute information data, one or a plurality of information datagroups having different attributes can be freely processed forrecording, reproduction, editing and so on. Further, by collectivelyrecording the management data in a predetermined management data regionand continuously recording information data groups having differentattributes in a predetermined information data region, a recordingregion is free from blank invalid regions, and a longer recording timecan be achieved.

While the foregoing embodiment has been described for arecording/reproducing apparatus which handles DVD-R/W, the presentinvention can be applied to apparatus which handle other kinds ofrecording disk media, and storage devices such as a semiconductor memoryor the like.

As described above in detail, according to the present invention, whencompressed digital data is recorded/reproduced using a variable bit ratecoding, even if information data which has undergone editing such aschapter setting, erasure or the like after recording is reproduced froma midway position, time information on reproduction at that position canbe derived.

1. A recording signal generating apparatus for receiving an informationdata piece and management data relating to said information data pieceto generate a data signal to be recorded on a recording medium, saidinformation data piece comprising a plurality of data cells, saidmanagement data including cell reproduction time periods of saidplurality of data cells, comprising: a divider for dividing saidplurality of data cells into a series of data units in accordance with apredetermined data format; a first calculator for calculating unit starttimings for the respective data units, each of the unit start timingsrepresenting a time period required for reproduction of data from a headposition of said information data piece up to a head position of each ofthe data units, a second calculator for calculating cell start timingsfor the respective data cells using the cell reproduction time periods,each of the cell start timings representing a time period required forreproduction of data from a head position of said information data pieceup to a head position of each of the data cells, a first modifier formodifying said information data piece by adding each of data pieceswhich represent the respective unit start timings to the correspondingdata unit in accordance with the predetermined data format to generate amodified information data piece; a second modifier for modifying saidmanagement data by inserting data representing the cell start timingsinto said management data in accordance with the predetermined dataformat to generate modified management data; and a generator forcombining said modified information data piece and said modifiedmanagement data to generate a data signal to be recorded on saidrecording medium.
 2. A recording signal generating apparatus accordingto claim 1, further comprising: a receiver for receiving a cell divisioninstruction which specifies one of the data units in one of saidplurality of data cells and instructs to divide said one of saidplurality of data cells; and an editor, in response to said celldivision instruction, for dividing said one of said plurality of datacells in two to edit said modified management data by inserting thereinthe unit start timing of a specified unit as a cell start timing.
 3. Arecording signal generating apparatus according to claim 1, furthercomprising: a memory for storing the reproduction time periods for saidplurality of data cells and the cell start timings; a third calculatorfor receiving an indication indicating a unit start timing of a unitwhich is under reproduction to calculate a reproduction elapsed timeusing the indicated unit start timing, stored reproduction time periodsfor said plurality of data cells and stored cell start timings.
 4. Amethod for generating a data signal to be recorded on a recordingmedium, comprising the steps of: receiving an information data piece andmanagement data relating to said information data piece, saidinformation data piece comprising a plurality of data cells, saidmanagement data including cell reproduction time periods of saidplurality of data cells; dividing said plurality of data cells into aseries of data units in accordance with a predetermined data format;calculating unit start timings for the respective data units, each ofthe unit start timings representing a time period required forreproduction of data from a head position of said information data pieceup to a head position of each of the data units, calculating cell starttimings for the respective data cells using the cell reproduction timeperiods, each of the cell start timings representing a time periodrequired for reproduction of data from a head position of saidinformation data piece up to a head position of each of the data cells,modifying said information data piece by adding each of data pieceswhich represent the respective unit start timings to the correspondingdata unit in accordance with the predetermined data format to generate amodified information data piece; modifying said management data byinserting data representing the cell start timings into said managementdata in accordance with the predetermined data format to generatemodified management data; and combining said modified informationwherein the steps of receiving, dividing, calculating unit starttimings, calculating cell start timings, modifying, and combining areperformed by a controller data piece and said modified management datato generate a data signal to be recorded on said recording medium.
 5. Amethod for generating a recording signal according to claim 4, furthercomprising the steps of: receiving a cell division instruction whichspecifies one of the data units in one of said plurality of data cellsand instructs to divide said one of said plurality of data cells; anddividing, in response to said cell division instruction, said one ofsaid plurality of data cells in two to edit said modified managementdata by inserting therein the unit start timing of a specified unit as acell start timing.
 6. A method for generating a recording signalaccording to claim 4, further comprising the steps of: storing thereproduction time periods for said plurality of data cells and the cellstart timings; receiving an indication indicating a unit start timing ofa unit which is under reproduction; and calculating a reproductionelapsed time using the indicated unit start timing, stored reproductiontime periods for said plurality of data cells and stored cell starttimings.
 7. A method for recording information data on a recordingmedium, the recording medium having an information data area and amanagement data area, comprising the step of: recording information datain the information data area, determining whether or not attribute dataof the information data is included in the existing management data inthe management data area, the attribute data indicating the reproductionscheme for the information data, and recording the management data inaddition to the existing management data, when it is determined that theattribute data of the information is not included in the recorded datain the management data area; and overwriting wherein the steps ofrecording, determining, and overwriting data are performed by acontroller the management data including attribute data identical to theattribute data of the information data when it is determined that theattribute data of the information data is included in the existingmanagement data.
 8. A recording apparatus for recording information dataon a recording medium, the recording medium having first informationdata and first management data for reproducing the first informationdata, the apparatus comprising: a recording device which records secondinformation data, and a controller, wherein the controller determineswhether or not the second data has an attribute identical to anattribute of the first information data, wherein if the secondinformation data has the identical attribute, the controller controlsthe recording device so as to overwrite the first management data, ifthe second information data has a different attribute from the attributeof the first information data, the controller creates second managementdata and controls the recording device so as to record the secondmanagement data.
 9. A recording apparatus according to claim 8, whereinthe first and second management data are recorded in a management dataarea.
 10. A recording apparatus according to claim 8, wherein the firstand second information data are recorded in an information data area.11. A recording method for recording information data on a recordingmedium, the recording medium having first information data and firstmanagement data for reproducing the first information data, the methodcomprising: recording second information data, and determining whetheror not the second data has an attribute identical to an attribute of thefirst information data, wherein if the second information data has theidentical attribute, overwriting the first management data, if thesecond information data has a different attribute wherein the steps ofrecording, determining are performed by a controller from the attributeof the first information data, creating second management data andrecording the second management data.
 12. A recording method accordingto claim 11, wherein the first and second management data are recordedin a management data area.
 13. A recording method according to claim 11,wherein the first and second information data are recorded in aninformation data area.